Instrument for testing the refraction of the eyes.



U. U. ALLEN. INSTRUMENT FOR TESTING THE REFRAGTION OF THE EYES.

APPLICATION FILED JAN. 23, 1914-.

Patented Nov. 10, 19M.

2 SHEETS-SHEER l.

f .w i K G. U. ALLEN. INSTRUMENT FOE. TESTING THE RBFRACTION OF THE EYES.

APPLICATION EILED JANJZS, 191 1.

Patented Nov. 10, 19M.

2 SHEETS-SHEET 2.

L used dam-Ala for *verilfyialgf accuracy f :1 vie iiappiiuation mm Qifaumary {63, 19M.

is, ASfiIGNDIL T0 GED.

CURPURATION U1 To all whom it may cmwwn Be it known that L Cum; U. Mumm, a citizen in the United States. mm a resment 0f (jhiqagu cmmty 01 (Jada and Mata (YE Minois, haw invented a certain new and iseful instrument f0 "fiwting Hm Hvwiruw Man Of the Eyas, of whicl'l aha fnflmvimg i=5 a. :fqmsificutiim.

My invent-i011 115m pniticuhu'h to the I wisimn of {militias for k'niniligthe in.- te my: of mm estimating; the r-eh'm "'0 prop wties or capabilities 0:? the 'ayms nbjmtiveiy W81} as snbjem'zivel n That is tn my, 1 desire to be able mam-min the power of refraction of the BF/"43 under examination in: dependently of What {be p:

12; orsubgect nmy report that he as the ZTGSLUL 0'55 QE- tiereni; adjustn'ients of the instr uncut. I reports oi the pmiient may Mid shmfld b flue abjeciive emmizmtiem.

The particular dbje of my prmmnt in. vention are whim PK'OViSiOD. of ifacflities or as" cert-aiming time reirzxctix-e properties the eye with Nfm'envv to the usual stzmflzwd for mbusss'i'z'ing such refraction, but gane'ml iy mm resg' ect t0 the entire eye. and; particuizuly with reapect to partial: meridians of the eye and of mg th "211G115 of the ey in an nphtwdmasmpic manner.

\ 3% HUMAN and exiirmmiy imifmflzmix objectmy, ei-went inveniii i5; 1%) Mimimm: the

Wmrkjug 01H, my gm. mini invention 1 em optical Fez-rim; ment which ul fx peimi 0f U1 use of a. n 211:3 of uninm and equal (ii inns.

I mmm the; above objects; by mamas oi the (11.1051111? i11u: :rafe& iv Hm :wcmn umying; 11: H1135? in which-- on m. flare from the: mummy E mil Serial No. 813E554.

with a wz'tii-afif vable uuhmup. 1 L beade l [12"!01', muted 11mm Mm alumni, and 111mm time; m'bmc nub-n.1, a pmmn 11m shown) which -odpa-n"aims upon the column t0 unntrol the Lmvm and lowering themnr'fl The instrument"gmpm is; :aunltully upon the top of 319 3 I mtmlprisml am out/s2 tube, scn gwically fife; an inner tub-m the lwuefssiu'y (:(H'ltii'dkd "etmwemrmt the #:ubea 6, the enter tube at 7, Where it is mount ed upon the. column slit, mm] mmmtecL so that its teeth exmnc} into this slit is gear. Q. The gear, 8 is; nunmteil upon an arbor. i); fn'nrnnlcd i'ln'nswi'seeiy 01 the K -files 5S and U in N10- top of the mlun'ny 2, and upon one vm'i (IF the :u'hm', it which erzizends in the PM? u? flw iumas. i xmmnijvd :2 band 1100! 10. The tube. (3, is pawwidafi W'Elfl n nu-k, 11. whu'h a-iz gyng 'esz with Hm m fi' e, and 1101mm W1! m the hflm. image i m-wing portion of the lvns =1 Obi-1m. to ma hereinafter referred 0. Entm'ing U1"? tube. (3. iuiemfly man it; umper nmL is a i'ulun 1 L in the rmtr and of which is mounted an ehmiiaiu light 1nd? 1:) amid a condensing 1011s 16, to mum-r the WW5; 01 light p'l'ncvetling from Hm bulb mpgwwzi mutely parallel.

In the tube, (3, and in i?"- and in flu: optical z the insfl'uuwnt. we {in :mgfleai Z? and 12-1. my? right ampfe; 3 'l'zmgg sd with their hv m'l gvtlwr, and the mcoting. the pyisn'ls'is WI'EQIILYUC! and part 4H tm'zdsnlisesi\'c 1., tinily cna 13. .115 it with si! :1 ma" war-4:21P 0* suhswamrfi sun.

Upon the surface, 20, of the prism, 18.

which is adjacent the end of the tube, 14, and at right angles to and in the path of the light proceeding from the bulb, 15), is a target, 21, visible lo the patient by reflection at the surface. 19. ihi'on h the lens element A a: in the tube, 12.

The surface, 19, snown as inclosed bem'een two prisms, 17 and 18, may con. i of one surface of a parallel plate, or of a prism, wlthin the spirit oi my invention. l have shown the optical system of my invention as composed of simple lenses, but any lillr; or 1 lenses may he fOlnleli oi more than one lens for the be ief CUlTdi'liiOD of spherical and chromatic abei'railons. The lens element mounted in the tube, 12, is composed of a i positive lens, 2:2, and a negative lens. 24, but a single positive element or any other suit able arrangemens may be employed without violating the princiiiles of of my invention.

In order to secure equal divisions upon the scale, 25, 1 construct the lens system upon the following optical principles: By

this arrangement a positive lens, if separated from the eye its focal length, anal if the eye be einmeh'opic, will render distinctly visible 9. target placed the focal length of the lens before the lens. When, for example,

By reason of the principle of auto-collimation an image of the image of the target, 21, formed the eye, is formed at the targefi,

2 The surface, 153', being" partially transm i e such an image 1s ais. formed at the Sui of "no 1?, which. is an equal zl.siaii ze from the. icficc'icing and teens milling surface, l5). and "from the IElLlIlfi of the eye upon which the image of the target, 21, is formed. properly see the image formed at 27, lhave provided an eye piece, entering the mile? cud oi the "lube, G.

in order to get llLl oi the reflection or flare from lhe sin-face oi i'h'e cornea and from the optical sin aces wilhin the instru n eni, which would, by reason of the glare thereof, ioially obscure the relatively dim image formed at 2'4", l have had recourse to the following aii'angome: ii is known L l at polarized light may he refleciefil at an oplicol sin-lace 03 at the cornea at angles olher than polarizing angles i 'ithout appreciuhlv ciing its properties, but that polarized ligin; illuniinat' a iliil'usi'ng surface, such as the i'el'ina, properlies ing from nolarization aye practically lost.

Utilizing ihese facts I have interposed a ,poiai'izing medium, in this case a Nicol the target is moved toward or away from the lens distance of one tenti, cwo tenths, three tenths, or n tenihs of the focal length of the lens the optical effect upon lhe eye will" be, respectively, minus 01- plus one fiemfih, ivvo tenths, three tenths, or 1., tenths of (lioptric power of the lens. if lens he of ten centimeters focus, on ion cliophers, than, in the above example, each linear movement of the target of one centimeter will produce a change of power at the eve of cxactly'one (liopter. i

Such an optical arrangement as is herein described permits me to use scale. 25, upon ihe periphery of the hand wheel, 16,013 eqnel and uniform divisions, which in coinhination Wiih a pointer, 26, iepenoling from the stationary outer tube, 5, "will indicate the change in refractive noise? in diogi'ters and fractions thereof. 4'

The lens elements, 22 ancl 24, perform the some function, optically, as the single n0sitive lens element referred to in che above emmpiewith the afivantage of securing larger field of view wiihin the observed eye which is of great importance when examin ing eye ophifiisimcscogiicaliy.

prism, 25), between the condensing lens, 16, and the target, 21. Such light, therefore, as is reflected from the optical surfaces within the instrument and the cornea, has ''he properties of polarized light, and will he extinguished by a polarizing analyzer, such as another Nicol prism, 30, conveniently located and disposed properly in the eye piece, 28, While the light illuminating the retina, having been depolarized, may be seen through the prism, 80.

In adjusting my instrument, all back reilcclions or flare may be extinguished by simply rotacing the eye piece 28, to th groper flare. While K have disclosed Nico-l prismshoclinient of my invention, XS manifest thatan y polarizing agencies may be employed without departing from the spirit of hi invention.

With astigmatic eyes. owing to the fact that the refractivepeo-tions oi the eye are unequal in diieifeni inei'nliens instead of spherical, it; nos possihie to focus on: image with critical defini i noon all meridians at the same aims. 1* 2 me i I facili' toting; the testing of astiginelio eyes and locating the ZDQTlCillTZS of s. and leastrefrnciion I have proviilcii in? target, :21, of the design shown in I 5, comprising the simple i'adiaiing lines. 31, in comhinm Lion with. the prolraetoe (lial. shown in Fig. 6, the central porlion. of which is clear. he pi'oli'aci-i' r (lllll, 32, is disposed noon the surface, 97, of ilie prism, 17, so

position which is easily determined i, the disappearance of no reflection or I as the polarizing agencies in the resent em that tm cmflin'zmad imz will zappem inihsa can I impos ad "1mm; "1:. .am a 3152 M with, shun PiGCfi With sash :m 151m s hwngesw m" MW afm mim'l is brm;

' tigmmzism; J

(fiffermue ham man a 25 for these Wm 1m 1*" My inveminn may \Li the eyes in flifiwmii; Wag v moscope, fur ul'imnim c iisregmml" 5519 im the pmtmw;

for estimsmlng regamfingg Mm 121 &5 adjusting; the ins 1 fereni; meriiiiams; (If the; U bined nbjec'izive and $111 "ecxiw manner almaifi y descriif1. opl'lthalmosmpm and, mpmma w results obtained by mmbhod may be direcfhr ms ts lobmined by t9. 11w

Having si i'escribm'i m Pat ent, is r 1. In an instrm mm :50}?

system.

In an instrnw a centered k age upon the for viewing said system simnltan-eolcisly with m 111 comparisml.

In an iIlShHYH L means "for projeuk. retina, mefl ms for view larizing dml'vice'anfl 2111 extinguishing all ing from the retina.

In an instrument @i the claw; (My-w means for lllumlna'tn'ag the 111130...

eye, means for 'viexvin g; the fa larizing device and an extinguishing light mflactmi at tervening between the: jected image of the :fundnc-g.

in am optics-11 in, forming bans system H111n"1atin;g' Hm ob 222i; 10 ma.

annlwn n Cuwice Indus,

with

n'lfg' said Sfifiili past it: said. 511m 111m upon said urban a mg); tha

Winn obtn'n -eii "say differ cmi iemz mmunmzd in the r 1 afiube, W10 righafi aughad hypommse aces tugaiihm' .1; of mid eye piece, the hf mid prisms being mu tube enterix'kg g opposite mic! Mn W316 with smii] and p, MW} transmit-- namm'tafii upon the me 043m 111m opwaning 01 said min 1': r'. prom'actnr scqjia 11pm mi m adjacent said aye piece,

tube Miami! 1 .uneni; for estixing the mfmm 'iizm z 'jHWTF-j 2h" eye 'nnmprmng a whutu d @1119. 11pm: saw v fiixgiun .1

u. fifiifl 11d seem: tuba, @IWG U primin with t'heir hypotenusw, 13mm; i immun zed. in mint of said eye; pi'aaca,

pal-Mia r eflective and pzn'tiuliy we :11": muminaiiup; tube entering; V m 1': hntemfly apposite MM "nu at l'fifi'zcting wi'z'ag'ie With midi iifm ifiv iiingj; m d pal-fiddly transmitaceq a targ et mountefii upon the 0'3? $11M pl-1am adjacent the awning of mid fllumhimlaingz; tube a prcatmctor scale upon 01 the prism adjacent, midi eye niece.

$3. in :m instrumem; for ms-1112155 his mftmw flies of 1e eye, a, lens @ystmn a I reflector for reflecting light 1mm tar 'et thrmaggh the 1mm fiystem, mews the image" of him projected ham oii muse njf one of mid prismwbeing;

get, and pohrizing dements ia' cerposeai the refiecio'r and nefism the viewi'ig meam.

9, In an in 'ruzni-nt of the 0525s clascz'ifiad .at'ingmea means for dimming-g the illunmmtion 'thmmgh said lens, maams "for viewing thwugh said lens fine flluminated as afm'esai, and for eliminating rm'bactioi area under emmimien comprisln izing' element is Med adjmeni; mating means, 'xolnirizi U element 100M661 'ante- 0 means rem the lens 2.13.16. the' five properties 0* the eye, a 142'. 3 system, refiefitnr reflecting light from t through the lens system, a promie we: fed at the point Where the age 0f the image is formed, and means for viewing the imag of the image of the tart and the pmtractor same simultaneously. testimnny wheyeof I afiix my signature the presence of 5W0 witnesses. g x I GLELYJ C. AL E 

